Wildlife & Habitat

Irwin Jesse 3 Puffins 512

 Castle Rock National Wildlife Refuge was established to preserve one of the most important seabird nesting colonies on the Pacific coastline. This 14-acre island continues to be preserved in a natural condition with minimal human intrusion. 

Castle Rock is unique among the more than 1,000 offshore rocks and islands in the state in that it has so many types of habitat on one large island within an extremely productive region of the Pacific Ocean. Castle Rock National Wildlife Refuge's habitat features include vegetated terraces, sheer rock cliffs, talus slopes, a tiny beach of pebbles, and reef habitat. These features allow it to host more than 100,000 breeding seabirds of 11 species, as well as provide haul out grounds for harbor seals, northern elephant seals, California sea lions, and Stellar's sea lions. The refuge also provides an important sanctuary for Aleutian cackling geese prior to their transoceanic migration.  


  • Common Murre

    Common murre and chick

    Common Murre are gregarious, clustering in dense colonies on the flat tops and wide ledges of islands. The birds nest shoulder to shoulder and may be so tightly packed that single birds returning from sea often land on the heads of others to settle in. A stark white breast contrasts sleek black feathers to create counter-shaded plumage on a bird that stands upright. Murres lay a single pear-shaped egg on bare ground. Castle Rock National Wildlife Refuge supports one of the most important colonies of Common Murres on the Pacific Coast.

  • Tufted Puffin

    Tufted puffin

    The Tufted Puffin is found along the Pacific Coast from Alaska to Southern California. They are charismatic members of the auk family with stout black feathered bodies, a white facial patch, large colorful bills, and two yellow head tufts. They dig burrows into the grassy slopes of offshore islands and raise a single puffling on small fish.  Tufted Puffins winter at sea and are rarely seen from land during that time. 

  • Pacific Harbor Seal

    Harbor seal basks in the sun

    The refuge serves as an important haul out (resting site) for marine mammals, including harbor seals and northern elephant seals who both bear pups there. In addition, the refuge is part of one of the largest resting sites for the California sea lion in northern California, and a key resting site for a local breeding population of the federally endangered Steller sea lion. The island is surrounded by waters rich with marine resources, this near shore habitat provides rich feeding grounds for the seals and sea lions. 

  • Steller Sea Lion

    StellersSeaLion LeValley 150

    The Steller sea lion (Eumetopias jubatus) is the largest member of the Otariid (eared seal) family. Males may be up to 325 cm (10-11 ft) in length and can weigh up to 1,100 kg (2,400 lb). Females are smaller than males, 240-290 cm (7.5-9.5 ft) in length and up to 350 kg (770 lb) in mass. Males and females are light buff to reddish brown and slightly darker on the chest and abdomen. Steller sea lion are distributed across the North Pacific Ocean rim from northern Hokkaido, Japan, through the Kuril Islands, Okhotsk Sea, and Commander Islands in Russia, the Aleutian Islands, central Bering Sea, and southern coast of Alaska, and south to the Channel Islands off California. During the May-to-July breeding season, Steller sea lions congregate at more that 40 rookeries, where adult males defend territories, pups are born, and mating takes place. The Stellar Sea Lion is listed as endangered by the Endangered Species Act.